This invention relates to a mechanism for sharpening a writing instrument, e.g. pencil, and in particular such a sharpening mechanism in which the length of the sharpened end of the writing instrument which may be inserted into the sharpening mechanism may be adjusted.
Pencil sharpeners have been made available for a very long period of time. While various modifications have been made to the outward appearance of such sharpeners to make them more aesthetically attractive, relatively few improvements have been made to the basic structure. Conventional pencil sharpeners include a generally conical insertion hole tapering from a broad outer entrance to a sharp inner end. This hole allows an end of a pencil to be inserted into the sharper, such that the pencil will be sharpened by a cutting blade secured to the sharpener when the pencil is rotated relative to, and moves into, the sharpener.
In one type of conventional pencil sharpeners, the inner end of the hole is not closed, such that the pencil may be caused to go on rotating relative to and moving into the insertion hole. The disadvantage of such an arrangement is that more than the necessary pencil may be cut away, or the user may not wish the pencil to be so sharp.
As an improvement, some pencil sharpeners are provided with a stopper at the inner end of the insertion hole so as to limit the inward movement of the pencil relative to the sharpener. By way of such an arrangement, once the pencil has proceeded to abut the stopper, further rotation thereof will not bring about any further inward movement of the pencil, so that no further pencil will be cut away. A disadvantage associated with such an arrangement is that the pencil sharpener cannot sharpen the pencil to a degree of sharpness which is up to the requirement of the user.
As yet a further improvement, some conventional sharpeners provide two insertion holes, each with a cutting blade, yet one without a stopper and one with a stopper. Not only does such an arrangement increase the cost of production, this type of pencil sharpeners also suffers from the shortcoming that basically only two degrees of sharpness are allowed.
It is thus an object of the present invention to provide an improved mechanism for sharpening an writing instrument in which the above shortcomings are mitigated, or at least to provide a useful alternative to the public.
According to the present invention, there is provided a mechanism for sharpening a writing instrument, which mechanism including a body member with a hole adapted to receive an end of said writing instrument, a cutting blade secured to said mechanism and adapted to sharpen said writing instrument, wherein said mechanism further includes a stopper movable relative to said body member to vary the length of said end of said writing instrument receivable into said hole.